Apparatus for automatically stunning animals to be slaughtered

ABSTRACT

Apparatus is provided for automatically electrically stunning animals to be slaughtered. The apparatus includes two V-shaped restrainers, where the second restrainer runs faster than the first restrainer to automatically space the animals apart. A pair of electrodes which are adapted to extend downwardly into the second V-shaped restrainer, are disclosed. The electrodes are specially shaped and are preferably adapted to transversely engage the head of the animal to be stunned. The electrodes are pivotally suspended from a reciprocating frame which is provided to move with the restrainer carrying an animal during the period that stunning is taking place, in order to maintain contact between the animal and the electrodes during the period of stunning.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.202,322, filed Oct. 30, 1980, now abandoned, which is a continuation ofapplication Ser. No. 905,371, filed May 12, 1978, now abandoned; thisapplication is also a continuation-in-part of application Ser. No.161,298, filed June 20, 1980, now U.S. Pat. No. 4,353,147, applicationSer. No. 147,826, filed May 8, 1980, application Ser. No. 147,827, filedMay 8, 1980, now U.S. Pat. No. 4,338,700, application Ser. No. 148,033,filed May 8, 1980, now abandoned, application Ser. No. 148,034, filedMay 8, 1980, now U.S. Pat. No. 4,319,383.

BACKGROUND OF THE INVENTION

The invention relates generally to apparatus for electrically stunninganimals to be slaughtered, such as pigs, sheep, cattle, and otheranimals which are slaughtered to produce meat usually for humanconsumption.

Before animals such as pigs are slaughtered, they should be renderedunconscious, or stunned. Stunning the animals before slaughtering helpsto prevent unnecessary animal suffering. Such stunning is desirablyaccomplished by applying an electrical shock to the animal. To renderthe animal unconscious, it is desirable to pass sufficient electricalcurrent through the animal's brain to result in a generalized epilepticinsult. In the past, the electrical shock has been induced by manuallyapplying electrodes to the animal. There has been a need in the art foran apparatus that can effectively stun animals automatically withoutrequiring manual placement of the electrodes.

In the past, manual methods have included utilization of a pair ofelectrical contacts, or stunning rods, which are held by a humanoperator against the head of an animal so that electrical current flowsfrom one electrical contact through the animal and to the otherelectrical contact. The stunning rods may be applied in a longitudinaldirection, relative to the animal's body, or in a direction transversethereto.

Manual stunning techniques have been plagued with problems, such as, theimproper application of electrodes to the animal, insufficient currentflow to effectively render the animal unconscious, the failure toimmediately evoke unconsciousness, the failure to prevent unnecessaryanimal suffering, and the failure to adequately protect the safety ofstunning equipment operators.

70 volts is a commonly used voltage for manual stunning methods. If ahuman equipment operator is to handle the electrodes used for stunning,it is desirable to keep the voltage as low as possible to minimize thedanger of electrocution to which the operator is exposed. In practice,it has been found that while 70 volts may immobilize a pig's neuromotorfunctions, electro-encephalographic traces showing the pig's brainactivity have revealed that a pig remains conscious after being stunnedwith only 70 volts. Such insufficient stunning is cruel and causesunnecessary animal suffering.

In pigs, it has been found that the current level generally necessary toachieve an immediate effective stunning in at least 90% of the pigstested was 1.07 ampheres. In practice, it has been found that 70 voltequipment fails to produce current levels of 1.07 ampheres in a pig.Increasing the voltage to a more dangerous level of 180 volts willsometimes produce a current level greater than or equal to 1.07ampheres, and sometimes will not produce the necessary current level.

The current flow required for stunning should pass directly through thehead of the animal at the correct potential and the correct intensity.It must pass through the head so that current will flow through theanimal's brain, instead of through the animal's muscle tissue. It mustbe at the correct potential and intensity to insure that the animal isrendered unconscious, not just merely immobilized.

Voltage levels as high as 300 volts and 525 volts have been used in thepast. However, the use of such voltage levels creates problems. As thevoltage is increased, the danger to human equipment operators isincreased. It is undesirable to force a man to handle electrodes withsuch high voltages present on the electrodes.

Also, when the voltage level is as high as 300 volts or 525 volts, ifthe electrodes are applied to the animal so that significant currentflows through the animal's muscles instead of its brain, severe musclecontractions can be induced in the animal. The muscle contractions canbe so severe that bone breakage and internal bleeding can occur.

Such severe muscle contractions cause unnecessary animal suffering. Inaddition, improper current flow during stunning should be avoidedbecause it can result in reducing the value of the meat of the animal tobe slaughtered. When muscular contractions occur in the animal, causingbone breakage and internal bleeding, the meat of the animal must usuallythen be classified as a lower quality or grade of meat.

High voltage current flowing through muscle tissue causes adverseconsequences including unfavorable post-mortem chemistry in the animalmeat. Such current flow through muscle tissue is believed to result inthe release of lactic acid in the meat tissue because of the severemuscle contractions. The lactic acid accumulation may have anunfavorable effect on the quality of the meat and can result in acondition commonly referred to in the art as pale-soft-exudative, ofP.S.E. The meat will have a poor color and appearance.

As the voltage level is increased the placement of the electrodesbecomes more critical in order to avoid high voltage current flowthrough the animal's muscle tissue. Manual stunning methods have anelement of uncertainty due to the manual application of the electrodes.

At low production rates, manual stunning techniques may result in a lowpercentage of animals that are not of prime quality due to internalbleeding and bone breakage caused by the improper application ofelectrodes. Manual stunning presents, however, the drawback of limitedproduction, because human operators in practice have not generally beencapable of production rates above a certain level of production withoutadverse effects on efficiency. Attempts to increase the production ratecan result in a significant increase in the incidence of misapplicationof the electrodes to animals. Furthermore, to avoid the situation wherethe animal to be stunned only loses consciousness momentarily, it isdesirable to use a high voltage which is believed to adversely affectthe human operator's safety.

For example, if a production rate of 600 pigs an hour were to beattempted, the human operator would have to stun an animal every sixseconds. This would create a great deal of stress upon a human operator,who must handle high voltage electrodes and quickly apply them to eachanimal's head while the animal may be squirming or trying to avoid theelectrodes. In practice, it has been found that the number of times thata human operator will improperly apply the electrodes, inducingconvulsions and resulting in low grade meat, increases substantially atsuch attempted production levels. In other words, a higher drop outpercentage results.

In the past, attempts to develop an automatic stunning apparatusresulted in a higher drop out percentage than that occurring from manualstunning even at slow production rates. That is, a greater percentage oflower quality grade meat was obtained from animals subjected to suchattempts at automatic stunning as compared to manual stunning. There hasbeen a long felt need in the art for an effective automatic stunningapparatus.

U.S. Pat. No. 1,857,658, issued to Pfretzschner, represents an attemptat an automatic stunning device. The flaps illustrated for use aselectrodes are intended to roll over the back or sides of the animal tobe stunned. Such a haphazard placement of electrodes would likely resultin violent convulsions and broken bones, with the resultant adverseeffects on meat quality.

It is important that animals be restrained during stunning so that theanimals are not touching each other. If one animal is touching anotheranimal that is being stunned, that animal will also receive a shock.Typically, the shock flows through muscle tissues and can causeconvulsions, creating the adverse consequences that result from suchconvulsions, including broken bones, internal bleeding, poor meatquality, and unnecessary animal suffering. The previously mentionedPfretzschner reference does not recognize this problem.

The present invention is believed to provide an automatic apparatus forelectrically stunning animals in which the drop out percentage is equalto or less than that achieved with manual stunning techniques. Thepresent invention is believed to provide an automatic apparatus capableof achieving production rates faster than are practicable with manualstunning.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an apparatusfor automatically electrically stunning animals, which includes a firstconveyor having two synchronously and parallel running endless conveyingbelts, the operating surfaces of which are positioned to form asubstantially V-shaped passageway therebetween. A floor is disposedbeneath the conveying belts in such a manner that the distance betweenthe floor and the belts generally increases in the direction of movementof the belts. In other words, as animals move down the V-shaped belts,the sloping floor drops out from under their feet leaving them heldsolely by the V-shaped belts.

The preferred embodiment of the apparatus further includes a pair ofelectrodes which are arranged side by side in the passageway and whichare of such a shape and have been mounted in such a manner that they areoperative to engage the sides of the head of the animal substantially atthe same time. In a preferred embodiment, the electrodes are positionedside-by-side rather than consecutively so that the electrical currentwill pass transversely through the brain of the animals to be stunned.

In the presently preferred embodiment, the two electrodes comprise twoplates, the outer portions of which are substantially parallel to eachother and are disposed adjacent to the respective operating surfaces ofthe conveying belts. The portions of the electrodes which face eachother diverge from the lower ends thereof in an upward direction up toabout half the height of said plates whereupon by means of a curvaturesaid latter edges merge into a converging portion. In other words, theelectrodes are shaped to conform to the contour of the head of ananimal.

Alternatively, the pair of electrodes may be disposed consecutively andoriented so that the distance between the electrodes remainssubstantially constant as an animal contacts the electrodes. In thislatter embodiment, each electrode includes a plurality of parallel rodsspanning the transverse distance between the conveying belts.

In one aspect of the present invention, the electrodes are pivotallysuspended from a reciprocating frame. When the electrodes simultaneouslycontact the animal's head, the reciprocating frame begins to move in thesame direction as the conveying belts at a velocity substantially equalto that of the belts. This maintains the electrodes in contact with thehead of the animal as the animal is moved by the conveying belts. Atfast production rates, this keeps the electrodes in contact with thehead of the animal longer to improve the effectiveness of the stun.

In another aspect of the present invention, a second V-shaped conveyoris provided after the first conveyor. The second conveyor is operated ata faster velocity than the first conveyor to ensure that adjacentanimals are spaced apart as they are transported by the second conveyorinto contact with the electrodes. This prevents a second animal fromreceiving a shock by being in contact with a first animal that is beingstunned.

These and other features and advantages of the present invention willhereinafter appear, and for purposes of illustration but not oflimitation, an exemplary embodiment of the present invention is shown inthe appended drawings and described in the following detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of a preferred embodiment of theinvention.

FIG. 2 illustrates an end view of the preferred embodiment shown in FIG.1.

FIG. 3 illustrates a side view of an embodiment of the invention, shownpartially in cross section.

FIG. 4 depicts an end view of the embodiment of FIG. 3, showing ananimal held in the V-shaped conveyor belts.

FIG. 5 illustrates a side view of an embodiment of the inventionemploying two consecutive V-shaped conveyor belts.

FIG. 6 is a partial side-elevational view, partially in cross section,of an apparatus for electrically stunning animals in accordance with apresently preferred embodiment.

FIG. 7 is a sectional view of the apparatus of FIG. 6 taken alongsection line 7--7 in FIG. 6.

FIG. 8 illustrates a presently preferred embodiment of an electrode inrear view.

FIG. 9 is a side view of the electrode of FIG. 8.

FIG. 10 shows seventeen different cross-sections of FIG. 9, illustratingthe slope and contour of the electrode.

FIG. 11 illustrates a flat development of a plate from which thepresently preferred embodiment of the electrode illustrated in FIGS.8-10 can be made.

FIG. 12 is a side-elevational view of an alternate embodiment of anelectrode arrangement.

FIG. 13 is a sectional view of the alternate electrode arrangement takenalong section line 13--13 in FIG. 12.

FIG. 14 is a diagrammatic cross-sectional view of portions of twoconveyor belts, such as the belts illustrated in FIG. 1.

FIG. 15 is a partial schematic diagram of a low power source, a fullpower source, and a switch.

FIG. 16 is a partial schematic diagram of a delay means interposedbetween the stunning power source and the electrodes.

DESCRIPTION OF A PRESENTLY PREFERRED EMBODIMENT

FIG. 3 illustrates a V-shaped conveyor belt 1, and shows how animals areherded toward the V-shaped belt 1 from the left (shown a 4 in FIG. 3). Afloor 3 is provided sloping downwardly so that as an animal is moved inthe direction indicated as 4 in FIG. 3, the floor 3 drops away from itsfeet until the animal is supported only by the V-shaped belt 1 and ismoved into contact with a set of electrodes 5 and 6. FIG. 4 shows howthe animal is supported by the V-shaped belt 1 as it is moved toward theelectrodes 5 and 6. Thus the animal is effectively restrained andautomatically carried into contact with a set of electrodes.

It is desirable to provide means for preventing animals from touchingeach other when one of the animals is brought into contact with theelectrodes. If one animal is touching another animal being stunned, thatanimal will also receive a shock that could cause convulsions, bonebreakage, internal bleeding, and unnecessary animal suffering. Thus,means should be provided to provide for the automatic spacing of theanimals. This is essentially accomplished in the present invention byproviding two sets of conveyor belts, as shown in FIG. 1 and in FIG. 5.

In the presently preferred embodiment illustrated in FIG. 1, thevelocity of the first restrainer 11 is lower than that of the secondrestrainer 12. In other words, the second restrainer 12 operates at afaster rate than the first restrainer 11 to ensure that the animals onthe second restrainer 12 are spaced apart. This arrangement provides forthe automatic separation of animals to facilitate the stunning of oneanimal without the application of a shock to the next-succeeding animal,which might otherwise be touching the animal that is being stunned. Theautomatic separation of the animals is further illustrated in connectionwith FIG. 3.

A brief description of the operation of the apparatus is as follows:Referring to FIG. 1, the animals are introduced in succession into theautomatic stunning apparatus from the left. The animals each in turn arecarried toward the right by the first restrainer 11. The floor 3 dropsout from under the animals, leaving them held only by the restrainer 11.The first restrainer 11 carries the animals to the second restrainer 12,which runs faster than the first restrainer 11. The animals areautomatically spaced apart on the second restrainer 12 and are carriedinto contact with electrodes 20 and 21, visible in FIG. 2.

When an animal contacts the electrodes 20 and 21, a sensing currentbegins to flow to automatically test whether the appropriate contact hasbeen made with the animal's head. The electrodes 20 and 21 arepreferably pivotally attached to a movable frame assembly 22. When ananimal contacts the electrodes 20 and 21, the frame assembly 22 beginsto move along with the animal in the direction of conveyance (shown as 4in FIG. 1) in order to maintain a longer contact between the electrodes20 and 21, and the animal. If the automatic test performed by theapparatus with the sensing current indicates that the appropriatecontact has been made, the full stunning current will be switched in andthe animal will be electrically stunned to render the animalunconscious.

The animals are released one by one from the second restrainer 12 in anunconscious state. The animals may be hung upside-down by their hindlegs and bled. If the animals have been correctly stunned, the animals'brain activity will cease due to loss of blood before the animals regainconsciousness, thus preventing unnecessary suffering by the animals. Theanimals may then be processed for slaughtering in a conventional manner.

The construction and operation of the apparatus will be betterunderstood by the detailed description that follows:

A set of electrodes are provided in cooperative association with thesecond restrainer 12. One embodiment of suitable electrodes isillustrated in FIGS. 6-7. A second embodiment of suitable electrodes isshown in FIGS. 8-10, and in FIG. 2.

FIG. 7 shows an end view of the second restrainer 12 having electrodes109 and 110 extending downwardly into the V-shaped passageway so thatthe electrodes 109 and 110 will contact an animal held between twoconveying belts 101 and 102. The electrodes 109 and 110 are arrangedside-by-side and are intended to contact the animal at substantially thesame time.

The electrodes 109 and 110 shown in FIG. 7 have horizontal under edges134 and 135, respectively. The electrodes 109 and 110 have outer sideedges 122 and 123 respectively running substantially parallel to thesurfaces of the conveyor belts 101 and 102, respectively. This shapeminimizes the chances of an animal putting its head into the gap betweenone electrode and the conveyor.

One problem with automatic stunning is that, while it is possible torestrain an animal's body with the V-shaped restrainer 12, it is notpractical to restrain the animal's head. Without a human operator toorient the placement of the stunning electrodes to accommodate variouspossible positions of the animal's head, in an automatic stunningapparatus it is desirable to induce the animal to place its head in theappropriate position between the electrodes.

In the embodiment of the electrodes 109 and 110 illustrated in FIG. 7,the electrodes have inner edges facing each other, the inner edgesincluding diverging lower portions 124 and 125 merging by means of acurvature 126 and 127 into converging portions 128 and 129,respectively. The converging portions 128 and 129 merge finally intoparallel edge portions 130. It has been found in practice that theanimal will seek to put its head through the space between the twoelectrodes, whereby the animal's snout will seek more or lessunintentionally the appropriate position with respect to the electrodes109 and 110 so that the electrodes 109 and 110 will pass across thesides of the snout and head.

In horizontal cross-section, each one of the electrodes 109 and 110 iscurved, the strongest curvature being present at the level of theportion 126 or 127 respectively. This curvature is such that, whenviewed in the direction of conveyance, the edges 126 and 127 will bepresent in front of the edges 122 and 123, respectively, and willpreferably form part of an arc. In the lower portion and in the upperportion, that is to say the portions having diverging edges 124 and 125,and converging edges 128 and 129, respectively, this curvature may beless pronounced.

It is conceivable that one may use an embodiment in which, when viewedfrom below, the lower portions of the electrodes 109 and 110 constituteflat planes positioned to form together a V-shaped border line, wherethe planes form this V-shape either through a change of angle with theupper portions of the electrodes 109 and 110, or by merging into acurvature.

In practice, the embodiment of the electrodes illustrated in FIGS. 6 and7 may sometimes leave traces on the skin of some types of animals. Thismay be undesirable.

A presently preferred embodiment of suitable electrodes is illustratedin FIGS. 8-10, and in FIG. 2. This embodiment of the electrodesminimizes the possibility of leaving traces upon the animal's skin,while at the same time achieving sufficient contact with the animal toeffectuate stunning.

In a preferred embodiment, two electrodes are fashioned as mirror imagesof each other as illustrated in FIG. 2 and in FIGS. 8-10. The twoelectrodes are placed side-by-side on the second restrainer 12 (seeFIGS. 1 and 2), generally in parallel relationship to each other. Theelectrodes are mounted so that they are pivotable around a generallyhorizontal transverse axis lying above the restrainer 12. The axis ofrotation lies in the center of a U-shaped portion 202 shown in FIG. 9.

Each electrode may be fashiond from a flat plate 201 of the shapeillustrated in FIG. 11. The flat plate 201 is provided with rounded offunder edges, as shown in FIGS. 8 and 9. The U-shaped portion 202 iswelded to the plate 201, and is fixed on a pivot shaft so that theelectrode may pivot about the axis of rotation. The rounded off underedges curve smoothly into an outer edge 203 on the diverging portion.The outer edge 203 of the plate 201 is nearly rectilinear over thegreatest part of its length, having a straight portion 208, but mergessmoothly into the curved point 204 in the final third portion through acurvature 215 having a very weak bending or small amount of curvatureinitially. The curved point 204 merges smoothly into the curvature orconverging edge portion 205 leading smoothly to a reverse bending 206merging smoothly into a straight portion 207 located opposite of thestraight portion 208 of the outer edge 203.

Rouding off the under edges of the electrodes minimizes the chances ofthe electrodes leaving traces on the back portion of the animal. Thesmoothly curved edges of the plate electrodes directed slantinglyfrontward are designed to provide good electrical contact with the headof the animal without leaving traces, even though the head of eachanimal may be in a different position and each animal's head may contactone electrode earlier than the other electrode.

The outer edges of each electrode extend substantially parallel to andin closed relationship along the operating surfaces of the conveyorbelts 101 and 102 to keep the animal from placing its head between anelectrode and a conveyor belt. The edges of the electrode which arefacing each other diverge in an upward direction from the under ends andmerge through a curvature into edges converging to each other. Theelectrodes when viewed in the direction of conveyance are seen as beingdirected slantingly downward and frontward from above such that theinner edges with respect to the outer edges are directed frontward frombeneath and subsequently run back again so that in the center portionviewed from above a V-shaped position (in the direction of advance) ofthe operating surfaces of the electrodes is obtained.

This may be better understood with reference to the cross section ofFIG. 9 taken along line h, which is illustrated in FIG. 10. Theelectrode, at the cross section taken along line h, forms an angle ofroughly 45° with a reference plane 209. The reference plate 209 isvertical and is transverse to the direction of advance of the animal.Because the two electrodes are generally mirror images of each other,the other electrode will also form an angle of roughly 45° at thecorresponding cross section. Thus, the two electrodes will, when viewedfrom above, form a V-shaped position at this cross section of theoperating surfaces.

If the preferred embodiment of the electrodes are oriented vertically,each electrode will be seen to be rectilinear in each cross sectiontaken in a horizontal plane parallel to the electrode's pivot axis. Thiscan be seen with reference to the cross sections illustrated in FIG. 10.Each rectilinear section with respect to the vertical reference plane209, which is parallel to the pivot axis, makes an angle with thereference plane 209. This angle when viewed from above overapproximately a third of the length of each electrode increases from asmall angle up to an angle of approximately 45°, over the center range.The center range is the range with the curvature of the inner edge lyingbetween the diverging and the converging portion of the electrodes. Inthe center range of the electrodes, the angle remains nearly equal, andthereafter decreases slightly again. The distance of the outer edge 203of each electrode from the reference plane 209 remains at firstsubstantially equal in the first one third part 208 of the length 203 ofthe electrode, decreases slightly thereafter, and then increases in thecenter range; this distance again decreases in the final portion 215 ofthe electrode.

So, over the entire height the electrodes form a generally V-shapedpassage in the direction of conveyance, which is wide open in the upperportion, becomes slightly narrower subsequently, and thereafter opensslightly again. Each electrode by its alternating distance of the outeredge from the reference plane 209 exhibits also a slight curvaturedirected frontward if viewed along the electrode from above.

The opening formed between the two electrodes by the curvature of theinner edge when the electrodes are in a condition of rest is an aperturethat is slightly lens-shaped. The opening is similar to the shape thatwould be formed by two big thumb free hands when the hands naturallygripped around the snout of an animal from above, with one hand on oneside of the snout and one hand on the other side of the snout.

In FIG. 10 the cross sections of the electrode are shown with respect tothe reference plane 209.

In the first cross sections a, b, c and d, the distances of the outeredge 208 from the reference plane 209 are equal. Similarly, the distanceof the inner edge 207 from the reference surface 209 is equal for thesecross sections. In the cross section e, the outer edge 203 becomesslightly closer to the reference plane 209, and this continues up to thecross section g. The inner edge 206 has a larger distance from thereference plane 209 in cross sections e and f. The distance of thecurvature 205 from the reference plane 209 as shown in the crosssections g, h and i remains nearly equal over these cross sections.However, at the same time the distance of the outer edge 203 from thereference plane 209 becomes larger, which continues up to the crosssection k. After cross section k, the distance from the inner edge 205and 204 to the reference plane 209 decreases again. Also, after crosssection k the distance between the outer edge 203, 215 and 204 to thereference plane 209 decreases again.

The different sections a up to and including q show clearly the trend ofthe angle of inclination and the variation of the distance from thereference plane 209 and give in this way in combination with FIGS. 8 and9 a picture of the three-dimensional profile of the electrodes.

The surface of the electrodes which comes into contact with the animalcan be provided with ridges 210 or similar raisings, as shown in thecross sections a, b and c illustrated in FIG. 10. Such ridges 210 areintended to increase the contact pressure of the electrodes onto theanimal. Increasing the contact pressure improves the passage of current,which may permit the stunning voltage to be lowered without adverselyaffecting the effectiveness of the apparatus. The ridges 210 preferablyextend in the direction in which the animal's head brushes past theelectrode, as illustrated in FIG. 8. However, the ridges 210 may extendin other directions without departing from the invention.

Although the electrodes have been described as preferably beingfashioned from flat plates 201, the electrodes may be manufactured bymolding or by casting, all as will be apparent to those skilled in theart after having the benefit of this disclosure. The ridges 210 may beformed upon the electrodes during casting. In manufacturing theelectrodes from plates 201, the ridges 210 may be formed from weldbeads, which may be ground or not, as desired.

An animal passing between the two electrodes will at some point contactboth electrodes. When the animal does so, a sensing current of lowvoltage will start to flow. This sensing current will be tested todetermine whether the proper resistance is presented between the twoelectrodes. By testing the sensing current, it is possible to tellwhether the animal contacting the electrodes is a pig or not. Every kindof animal presents its own specific resistance to the sensing currentflow. Thus, each kind of animal will allow a different level of sensingcurrent to flow. If the sensing current is found to be at theappropriate level, so that the apparatus is able to automaticallydetermine both that the right kind of animal is present between theelectrodes and that the electrodes are engaging the head of the animalin the proper way, then the main current will be automatically switchedin and stunning will occur. This eliminates the need for humanobservation and decision.

At high production rates, the animals will be moved quickly through theapparatus. It is desirable to move the electrodes along with the head ofthe animal in order to lengthen the amount of time that the electrodesare in contact with the head of the animal. This is essentiallyaccomplished in the present instance with the apparatus illustrated inFIGS. 1, 2, 6 and 7.

Referring to FIG. 7, on top of frame 103 of the apparatus, which is onlyindicated schematically, is affixed frame 104. The frame 104 includeslower and upper members 131 and 132 respectively having U-shaped crosssections, the flanges of which face each other. The flanges of theU-shaped members 131 and 132 are provided with V-shaped rail surfaces105 and 106. Between the rail surfaces 105 and 106 are accommodatedrunners 107. The guide surfaces 105 and 106 may be coated with a teflonlayer or the like to reduce noise caused by the travel of the runners107 over the guide surfaces 105 and 106.

The two electrodes 109 and 110 are suspended from frame 108 and extenddownwardly into the V-shaped passageway. Electrodes 109 and 110 arepivotally mounted on a shaft 111 and are each hingedly coupled to adampening member 113 (FIG. 8) by rod 112.

The dampening members 113 dampen at least the upward movement ofelectrodes 109 and 110, and the counteracting resistance of thedampeners helps maintain good contact between the electrodes 109 and 110and the moving head of the animal. Upon passage of the stunned animal,the dampeners 113 cause the electrodes 109 and 110 to return to theirinitial position, thus permitting the time between stunning ofsuccessive animals to be kept small in order to achieve a sufficientlyfast production rate. It is to be understood that a single dampeningmember 113 may be provided for simultaneously dampening the movement ofthe two electrodes 109 and 110 and still remain within the contemplationof the present invention.

The dampening members 113 are hingedly fastened to the frame 108 at 114.In a way not shown but known to those skilled in the art, the electrodes109 and 110 are insulated with respect to each other on the shaft 111 aswell as with respect to the frame 108 and are connected to suitablecurrent conductors.

Mounted on frame 104 are supports 115 which support driving means 116,such as a hydraulic cylinder, and a motor-driven pump 117 coupledthereto. A piston rod 118 of the cylinder 116 is coupled through a lever119 to the frame 104 and to the frame 108 at 120 and at 121,respectively. A movement of the piston rod 118 in a direction oppositeto the direction of movement of the conveying belts causes movement ofthe frame 108 together with the electrodes 109 and 110 in the directionof conveyance of the animal.

When a flow of current occurs between the electrodes 109 and 110, orafter some predetermined time delay, a normal switching circuit (notshown) switches on drive motor 117, whereby hydraulic cylinder 116extends piston rod 118 at a velocity causing frame 108 to move at avelocity substantially equal to that of conveying belts 101 and 102.Thus, the reciprocating frame 108 enables the electrodes 109 and 110 tomaintain proper contact with the head of the animal during the period ofstunning.

The reversal of the motor 117 and the cylinder 116, and the frame 108may be controlled by a time switch or by a limit switch mounted on astop disposed at a predetermined distance downstream from the initialposition of frame 108.

At a desired production level of 600 pigs per hour, for example, sixseconds are allocated for stunning an animal. One to four seconds arerequired for actual stunning, leaving a sufficient amount of time forthe return movement of frame 108. The reciprocating movement of theframe 108 lengthens the amount of time that the electrodes are incontact with the head of the animal, so that one to four seconds ofcontact time may be provided even at fast production rates.

Those skilled in the art should appreciate that other electrodearrangements like that illustrated in FIGS. 3, 4, 5, 12 and 13, such asa consecutive arrangement, may be used with the reciprocating frame 108and still remain within the contemplation of the present invention.

In one such alternate embodiment, when viewed from below, the lowerportions of the electrodes may constitute flat members positioned toform a V-shaped configuration, either maintaining said V-shape though ata change of the angle or merging into a curvature.

In still another alternate embodiment, the electrodes may be arrangedconsecutively as shown in FIG. 12, and each electrode may comprise aplurality of parallel rods which are pivotally suspended from a commonshaft as shown in FIG. 13.

With reference to FIG. 12, shown are a first set of electrodes 303 and asecond set of electrodes 304, each set including three separateelectrodes, as shown in FIG. 13, which extend down into the passagewaybetween the conveyors 301 and 302 in such a manner that the main part ofthis passageway is obstructed.

Each of electrodes 303 may be independently operable to pivot about ahorizontal shaft 305, and may be biased by spring means 306.

In a similar manner, each of electrodes 304 are independently operableto pivot about a horizontal shaft 307 and are biased by spring means308.

The bearings of the shafts 305 and 307 and the springs 306 and 308 areaffixed to a plate 309, which is in turn affixed to supports 310 mountedon frame 311 (not shown in detail) of the conveyor apparatus. Tubes 312may form an upper restriction of the conveyor apparatus.

At the lower end thereof, each one of the electrode arms 303 is providedwith a small bent electrode contact portion 313 which is connected to acable 314 provided in the electrode arm.

On the side facing the first electrode, each one of the electrode arms304 is covered by a conductive contact portion 315 which is connected toa cable 316.

As shown in FIG. 12, the sets of electrodes may be pivoted upwardentirely to the horizontal position to enable a stunned animal to passthereunder. FIG. 6 shows both sets of electrodes in their initialposition. An animal arriving from the left-hand side, with respect tothe orientation shown in FIG. 12, causes at least one of the arms 303,including the electrodes 313, to pivot upward without causing asubstantial change in distance relative to the electrode arms 304 andthe electrodes 315. As soon as the animal contacts an electrode 315, thecurrent circuit is closed.

The distance between the sets of electrodes may be adjusted in adirection coinciding with the travel of the conveyor. Furthermore, it iswithin the contemplation of the present invention to conditionapplication of the jolt of the current on the animal displacing thesecond electrode over an arc having a length equal to a predeterminedangle as opposed to automatically applying the jolt of current at themoment that the animal simultaneously contacts both electrodes.

In order to prevent an animal from getting one of its legs trapped inthe transition area between the two restrainers 11 and 12, illustratedin FIG. 5, it is desirable to guide the animal across the transitionarea. In the present instance this is provided by guide rollers 409 and410 shown in FIG. 14. FIG. 14 illustrates a cross section of thetransition area of two conveyor belts. Preferably, the guide rollers 409and 410 are positioned so that they are tangential to the planecoincident with the operating surfaces of the consecutive conveyingbelts. The guide rollers may be freely rotatable or they may be drivenat such a velocity that their peripheral velocity is substantially equalto the velocity of the preceding (upstream) conveyor. This latteralternative avoids further conveyance of an animal past the transitionarea whenever the first conveyor 11 is stopped due to an excess ofanimals being transported onto the second conveyor 12.

Alternatively, each conveying belt may comprise a plurality of curvedconveying plates, as illustrated in FIG. 14.

The conveyor means shown in FIG. 14 includes two chains, i.e, an upperchain and a lower chain, each one of the chains having links 401 andhinge shafts 402. Each one of the links may possess a lip 403 on which aplate 404 is mounted.

Each one of the plates may include front edge 405 having a circularcross section, the circular front edge being concentric with the hingeshaft 402, and a rear edge 406 which has a curvature of about a quarterof a circle and being likewise concentric with the shaft 402.

At the location of the reversing wheel (not shown), the axis of which isindicated at 407, the plates are hinged about each other without a gapbeing formed between the plates. The plates possess a curved operatingsurface 408, the radius of curvature of which corresponds to the arc ofrotation about the reversing wheel so that the operating surface willrun concentrically with the axis 407 at the location of the reversingwheel. The curvature of the surface of the plates promotes theentrainment of the animals.

Referring to FIG. 15 the apparatus of the present invention may also beprovided with means 11 for controlling the power supplied to electrodes5 and 6. The means 11 may comprise a control device 11 that isconstructed such that the full power 12 is switched in after a currentwith a low power 13 has originated from one of the electrodes 6 to theother 5, as shown in FIG. 15. In a presently preferred embodiment, ananimal is contacted by both the electrodes substantially at the sametime. Thereupon, a sensing current will start to flow, indicatingwhether the proper resistance is present. As every different kind ofanimal presents a specific resistance, it is possible to determine whena proper contact has occurred between the animal's head and theelectrodes before applying the stunning jolt. When proper contact isestablished, the full current is switched in, and stunning occurs.

The apparatus may also include a device for controlling the powersupplied to the electrodes 5 and 6 which is constructed such, that afterhaving delivered the full power during a short period, that is, afterhaving delivered a rush of current necessary for one stunning, thedevice is locked by a time delayed means 14 from delivering a next rushof current during a certain longer period, as shown in FIG. 16. Thus, asis the case where the consecutive electrode arrangement is employed, anext-succeeding animal does not receive a shock too early if it comes incontact with the first electrode while the second electrode is still incontact with the preceding animal. As discussed above, this problem mayalso be alleviated by utilizing the preferred two conveyor embodiment,which is illustrated in FIG. 1.

In accordance with the present invention, automatic stunning may beattained at a drop out percentage that is lower than that achieved bymanual stunning, particularly in manual stunning wherein the electrodesare placed upon the animal's head in a transverse manner. Whilemaintaining a low drop out percentage, a considerably faster productionrate of high quality grade meat may be achieved.

It is to be understood that the invention will admit of otherembodiments. The description herein of various embodiments of theinvention is given only to facilitate understanding of the invention bythose skilled in the art, and should not be construed as limiting theinvention.

What is claimed is:
 1. An apparatus for electrically stunning animals tobe butchered, comprising:a pair of endless conveyor belts, said beltsbeing positioned to form a substantially V-shaped passagewaytherebetween, said V-shaped passageway being adapted to receive ananimal, said belts being operable to run at a first synchronized rate,said belts being adapted to hold the animal fixedly with respect to saidbelts; a floor beneath said belts, said floor being inclined downwardly,said floor having a distance between said floor and said belts, saiddistance between said floor and said belts being generally increasing inthe direction of movement of said belts; a frame, said frame beingadapted to support said belts; a first electrode, said first electrodebeing supported by said frame, said first electrode being adapted toextend downwardly into said V-shaped passageway; a second electrode,said second electrode being supported by said frame, said secondelectrode being electrically isolated from said frame, said secondelectrode being adapted to extend downwardly into said V-shapedpassageway, said first and second electrodes being adapted toautomatically engage the head of an animal supported between the belts,said first and second electrodes being adapted to permit thetransmission of stunning current to the animal when said first andsecond electrodes simultaneously engage said animal; the first andsecond electrodes being arranged side by side in the V-shaped passagewayand being formed as mirror images of each other, the first and secondelectrodes having outer edges substantially parallel to and near to theconveyor belts to minimize the chances of an animal putting its headinto the gap between an electrode and a belt, the first and secondelectrodes having curved inner surfaces which diverge from each otherand then converge toward each other to form an opening through which ananimal may place its head, thereby unintentionally seeking to place itshead into a position for favorable electrical contact between theelectrodes and the animal's head; and, said belts, said floor, saidframe, said first electrode and said second electrode being mutuallycooperable to permit automatic stunning of the animal by moving theanimal into engagement with said first and second electrodes whilemaintaining the animal in separate relation to other animals to bestunned and while preventing the animals from moving with respect toeach other after the animals are received by said belts.
 2. An apparatusfor electrically stunning animals to be butchered, comprising:a pair ofendless conveyor belts, said belts being positioned to form asubstantially V-shaped passageway therebetween, said V-shaped passagewaybeing adapted to receive an animal, said belts being operable to run ata first synchronized rate, said belts being adapted to hold the animalfixedly with respect to said belts; a floor beneath said belts, saidfloor being inclined downwardly, said floor having a distance betweensaid floor and said belts, said distance between said floor and saidbelts being generally increasing in the direction of movement of saidbelts; a frame, said frame being adapted to support said belts; a firstrigid electrode, said first electrode being supported by said frame,said first electrode being adapted to extend downwardly into saidV-shaped passageway; a second rigid electrode, said second electrodebeing supported by said frame, said second electrode being electricallyisolated from said frame, said second electrode being adapted to extenddownwardly into said V-shaped passageway, said first and secondelectrodes being adapted to automatically engage the head of an animalsupported between the belts, said first and second electrodes beingadapted to permit the transmission of stunning current to the animalwhen said first and second electrodes simultaneously engage said animal;said first electrode and said second electrode being positioned side byside in said V-shaped passageway, said first electrode having an outeredge positioned near one of said belts, said second electrode having anouter edge positioned near the other one of said belts, the firstelectrode and the second electrode having inner edges which define anopening in said V-shaped passageway through which an animal may placeits snout; and, said belts, said floor, said frame, said first electrodeand said second electrode being mutually cooperable to permit automaticstunning of the animal by moving the animal into engagement with saidfirst and second electrodes while maintaining the animal in separaterelation to other animals to be stunned and while preventing the animalsfrom moving with respect to each other after the animals are received bysaid belts.
 3. An apparatus for electrically stunning animals to bebutchered, comprising:a pair of endless conveyor belts, said belts beingpositioned to form a substantially V-shaped passageway therebetween,said V-shaped passageway being adapted to receive an animal, said beltsbeing operable to run at a first synchronized rate, said belts beingadapted to hold the animal fixedly with respect to said belts; a floorbeneath said belts, said floor being inclined downwardly, said floorhaving a distance between said floor and said belts, said distancebetween said floor and said belts being generally increasing in thedirection of movement of said belts; a frame, said frame being adaptedto support said belts; a first set of electrodes, said first set ofelectrodes comprising a first pair of substantially parallel rods, thefirst pair of parallel rods being adapted to extend downwardly into saidV-shaped passageway, the first pair of parallel rods being spaced aparttransversely in said V-shaped passageway a sufficient distance to allowthe animal's head to pass therebetween, one of the rods being locatedsufficiently close to one of the endless conveyor belts to inhibit ananimal from attempting to place its head between the rod and the belt,the other of the rods being located sufficiently close to the other ofthe endless conveyor belts to inhibit an animal from attempting to placeits head between the rod and the belt, the first pair of parallel rodsbeing supported by said frame, the first set of electrodes being adaptedto engage the head of an animal; a second set of electrodes, said secondset of electrodes comprising a second pair of substantially parallelrods, the second pair of parallel rods being adapted to extenddownwardly into said V-shaped passageway, the second pair of parallelrods being spaced a distance from said first set of electrodes in thedirection of movement of said belts, the second pair of parallel rodsbeing spaced apart transversely in said V-shaped passageway a distancesubstantially equal to the distance between an animal's eyes, the secondset of electrodes being adapted to engage an animal's head near itseyes, the second set of electrodes being supported by said frame; saidfirst and second sets of electrodes being adapted to permit thetransmission of stunning current to the animal when said first andsecond electrodes simultaneously engage said animal; and, said belts,said floor, said frame, said first set of electrodes, and said secondset of electrodes being mutually cooperable to permit automatic stunningof the animal by moving the animal into engagement with said first andsecond electrodes while maintaining the animal in separate relation toother animals to be stunned and while preventing the animals from movingwith respect to each other after the animals are received by said belts.4. The apparatus according to claim 2, wherein:said frame furthercomprises a plurality of horizontal shafts; said first electrode ispivotally connected to one of said shafts; and said second electrode ispivotally connected to one of said shafts.
 5. The apparatus according toclaim 2 or 4, further comprising:a first spring, said first spring beingconnected between said frame and said first electrode, said first springbeing adapted to maintain said first electrode in an initial positionbetween said belts; and, a second spring, said second spring beingconnected between said frame and said second electrode, said secondspring being adapted to maintain said second electrode in an initialposition between said belts.
 6. The apparatus according to claim 3,wherein:said first set of electrodes is maintained initially in avertical position; and, said second set of electrodes is maintainedinitially in a generally downwardly sloping position, wherein saidsecond set of electrodes slopes generally downwardly and away from saidfirst set of electrodes.
 7. The apparatus according to claim 2 or 4,further comprising in combination:a power supply control, said controlbeing adapted to switch a full amount of power to said first and secondelectrodes after a current at a lower power level has flowed for apredetermined period of time between said first and second electrodes.8. The apparatus according to claim 2 or 4, further comprising:a secondpair of endless conveyor belts, said second belts being positioned aftersaid first pair of belts, said second pair of belts being positioned toform a V-shaped passageway therebetween, said second belts beingoperable to run at a second synchronized rate, said second synchronizedrate being faster than said first synchronized rate; and, wherein saidfirst and second electrodes are located proximately to said second beltsso that the electrodes contact the animals while the animals are beingheld in the second belts; said floor, said first belts and said secondbelts being mutually cooperable to ensure an adequate separation ofanimals moving through the apparatus; and, said floor, said first beltsand said second belts being mutually cooperable with said first andsecond electrodes to permit automatic stunning of the animals withoutstopping said first and second belts from running.
 9. The apparatusaccording to claim 5, further comprising:a second pair of endlessconveyor belts, said second belts being positioned to precede said firstpair of belts, said second pair of belts being positioned to form aV-shaped passageway therebetween, said second belts being operable torun at a second synchronized rate, said second synchronized rate beinglower than said first synchronized rate; and, wherein said first andsecond electrodes are located proximately to said second belts so thatthe electrodes contact the animals while the animals are being held insecond belts; said floor, said first belts and said second belts beingmutually cooperable to ensure an adequate separation of animals movingthrough the apparatus; and said floor, said first belts and said secondbelts being mutually cooperable with said first and second electrodes topermit automatic stunning of the animals without stopping said first andsecond belts from running.
 10. The apparatus according to claim 6,further comprising:a second pair of endless conveyor belts, said secondbelts being positioned after said first pair of belts, said second pairof belts being positioned to form a V-shaped passageway therebetween,said second belts being operable to run at a second synchronized ratebeing faster than said first synchronized rate; and, wherein said firstand second sets of electrodes are located proximately to said secondbelts so that the electrodes contact the animals while the animals arebeing held in the second belts; said floor, said first belts and saidsecond belts being mutually cooperable to ensure an adequate separationof animals moving through the apparatus; and, said floor, said firstbelts and said second belts being mutually cooperable with said firstand second set of electrodes to permit automatic stunning of the animalswithout stopping said first and second belts from running.
 11. Theapparatus according to claim 7, further comprising:a second pair ofendless conveyor belts, said second belts being positioned after saidfirst pair of belts, said second pair of belts being positioned to forma V-shaped passageway therebetween, said second belts being operable torun at a second synchronized rate, said second synchronized rate beinglower than said first synchronized rate; and, wherein said first andsecond electrodes are located proximately to said second belts so thatthe electrodes contact the animals while the animals are being held insecond belts; said floor, said first belts and said second belts beingmutually cooperable to ensure an adequate separation of animals movingthrough the apparatus; and said floor, said first belts and said secondbelts being mutually cooperable with said first and second electrodes topermit automatic stunning of the animals without stopping said first andsecond belts from running.
 12. The apparatus according to claim 3,wherein:said first set of electrodes is maintained initially in avertical position; said second set of electrodes is maintained initiallyin a generally downwardly sloping position, said second set ofelectrodes being generally sloped downwardly and generally in thedirection of movement of said belts; and, said first and second sets ofelectrodes being mutually cooperable to automatically permit thetransmission of a stunning current generally through the brain of theanimal, said first set of electrodes being alignable in contact with thebackside of the head of the animal when said second set of electrodescontacts the animal generally in the region of the face of the animal.13. The apparatus according to claim 2, further comprising:time delaymeans electrically interposed between said electrodes and a source ofstunning current for electrically disconnecting said electrodes fromsaid source for a predetermined period of time after the animal isstunned.
 14. An automatic stunning apparatus, comprising:a firstrestrainer formed by a pair of conveyor belts, the pair of belts beingpositioned to form a first substantially V-shaped passagewaytherebetween, the first restrainer being adapted to receive an animaland to move the animal at a first rate of speed; a second restrainerformed by a pair of conveyor belts, the pair of belts being positionedto form a second substantially V-shaped passageway therebetween, thesecond V-shaped passageway being generally aligned with the firstV-shaped passageway, the second restrainer being positioned next to thefirst restrainer so that animals conveyed by the first restrainer areautomatically transferred to the second restrainer, the secondrestrainer being adapted to receive an animal from the first restrainerand to move the animal at a second rate of speed faster than the firstrate of speed, thereby automatically separating animals from each otherwhile such animals are being conveyed by the second restrainer; a pairof electrodes pivotally suspended from a reciprocating support, thereciprocating support being located so that the electrodes contact ananimal while the animal is being held in the second restrainer, thereciprocating support having an initial position, the reciprocatingsupport being adapted to move in the direction of conveyance when ananimal contacts the electrodes at a velocity substantially equal to thesecond rate of speed of the second restrainer to maintain the electrodesin contact with the animal as the animal is moved by the secondrestrainer, the reciprocating support being adapted to return to itsinitial position after the animal has been stunned to position theelectrodes for another animal; a sensor to detect when an animal hascontacted the electrodes; and, the pair of electrodes being positionedso that the electrodes extend downwardly into the second V-shapedpassageway, the electrodes being positioned side-by-side in a plane thatis generally perpendicular to the direction of conveyance, theelectrodes being formed in a mirror image of each other, the electrodeshaving an outer edge substantially parallel to the conveyor belts of thesecond restrainer to minimize the chances of an animal putting its headinto the gap between an electrode and a conveyor belt, the electrodeshaving inner curved surfaces with edges which first diverge from eachother and then converge toward each other, the curved inner surfacesbeing shaped to present an opening through which an animal may seek toput its snout and thereby unintentionally position its head in aposition so that a favorable electric current path may be establishedbetween the pair of electrodes through the head of the animal.
 15. Theautomatic stunning apparatus of claim 14, further comprising:a springattached to at least one of the pivotally suspended electrodes, theelectrodes being adapted to swing away from an initial position to allowan animal to pass by the electrodes after it has been stunned, thespring being adapted to urge the electrode toward its initial position;and, a dampening member connected to said electrode to dampen movementof the electrode in order to improve electrical contact between theelectrode and the animal.